RNA结合蛋白Tdp43在乳脂分泌调控中的功能及其分子机制研究

The secretion of sufficient lipid in mammary tissue during lactation is essential for the growth and development of the offspring. There are many gaps in the understanding of the regulation mechanisms of milk lipid secretion, especially on the molecular regulation mechanisms of the core factors. Our previous study found that RNA binding protein Tdp43 is essential in milk lipid secretion: loss of Tdp43 function leads to failure of secretion of lipid from cells into vesicles and lumen, which results in about half of infant mice cannot survive due to nutritional deficiencies. In order to further analyzing the functions and molecular mechanisms of Tdp43 in milk lipid secretion, we will use the Tdp43 conditional knockout mice to carry out in-depth analysis of the phenotypes, especially the effects of loss of Tdp43 on milk lipid secretion; reveal the molecular mechanisms of Tdp43 in regulating key lipid secretion genes (XOR/Btn1a1) through the post transcriptional way; Owing to induced high expression of Tdp43 by applying progesterone in ovariectomized mice, we will confirm this by performing the cell and animal experiments and explore the molecular mechanism of regulation. The study will deepen people's understanding of the regulatory mechanisms of the milk lipid secretion process.

乳腺组织在哺乳期分泌充足的脂质对于后代的生长发育至关重要。人们对乳脂分泌的调控机制，尤其对其中核心因子的分子调控机制的认识还有很多空白区域。我们前期研究发现RNA结合蛋白Tdp43在乳脂分泌中不可或缺：Tdp43功能缺失导致乳脂不能由泌乳细胞分泌进入泌乳小泡和乳腺管腔，进而导致母鼠的泌乳障碍，致使约一半幼鼠因营养缺乏而不能存活。为了进一步解析Tdp43在乳脂分泌调控中的功能及其分子机制，我们将利用Tdp43条件性基因敲除小鼠开展深入的表型分析，研究Tdp43的功能缺失对于乳脂分泌的影响；揭示Tdp43通过转录后调控的方式影响乳脂分泌关键基因（Xor/Btn1a1）蛋白表达水平的具体分子机制；鉴于在卵巢切除小鼠中外施孕激素诱导Tdp43高表达，我们将从细胞和动物实验层面确认Tdp43受孕激素诱导，并探究其调控的分子机制。该研究将深化人们对于乳脂分泌过程调控机制的认识。

乳腺组织在哺乳期分泌充足的脂质对于后代的生长发育至关重要。人们对乳脂分泌的调控机制，尤其对其中核心因子（Btn1a1 和 Xor）的分子调控机制的认识还有很多空白区域。我们前期研究发现RNA结合蛋白Tdp43在乳脂分泌中不可或缺，Tdp43功能缺失导致乳脂不能由泌乳细胞分泌进入泌乳小泡和乳腺管腔，进而导致母鼠的泌乳障碍，致使约一半幼鼠因营养缺乏而不能存活。为了进一步解析Tdp43在乳脂分泌调控中的功能及其分子机制，我们利用Tdp43条件性基因敲除小鼠开展深入的表型分析，研究Tdp43的功能缺失对于乳脂分泌的影响；揭示Tdp43通过转录后调控的方式影响乳脂分泌关键基因（Xor/Btn1a1）蛋白表达水平的具体分子机制；鉴于在卵巢切除小鼠中外施孕激素诱导Tdp43高表达，我们将从细胞和动物实验层面确认Tdp43受孕激素诱导，并探究其调控的分子机制。上述研究结果于2020年发表在国际期刊Nature Communications (TDP-43 facilitates milk lipid secretion by post transcriptional regulation of Btn1a1 and Xdh)。关键结果包括：TDP43在哺乳动物谱系中经历了阳性选择；TDP43基因缺失会导致大脂滴和脂质体的积聚肺泡腔外的乳腺上皮细胞，进而导致严重脂质分泌不足，最终导致哺乳失败和产后三周内幼崽饥饿；哺乳期妇女的母乳样本中，TDP43的表达水平与母乳产量正相关；在机制上，TDP-43发挥转录后作用调节Btn1a1和Xdh mRNA的稳定性，这是脂质从上皮细胞到管腔分泌所必需的。综上所述，我们的阐明了TDP43在乳脂分泌中的作用，为临床上泌乳不足问题提供了一种潜在的干预靶点。